1. Field of the Invention
This invention relates to shade arrangements for a motor vehicle with at least one shade length and at least one roller tube for taking-up and unrolling the shade length, the shade length being guided along its side edge regions by at least one flexible, flat guide strip which extends along the drawing direction of the shade and is guided in a guide.
2. Description of Related Art
Shade arrangements for use in automotive construction are used, for example, as sun protection under a transparent vehicle body surface or also as a cover for the trunk space in a station wagon. These arrangements generally consist of a shade length which on its one end is wound onto a roller tube and which is tensioned by the reset force of the roller tube. The other end of the shade length is conventionally attached to a pull which can be moved by an electric drive or by hand, by which the shade length is accordingly drawn or rewound.
However, when the shade length on such a shade arrangement is tensioned only between the pull and the take-up roller, even with relatively high tension in this direction, for example, for a partially opened roof opening over the shade length the latter can flutter. Furthermore, the gap which is generally present in these embodiments on the edge of the shade length can be optically disruptive.
To overcome these disadvantages, shade systems are known in which the shade length is tensioned not only along its drawing direction, but also transversely thereto. Thus, for example, German Patent Application DE 197 39 919 A1 and corresponding U.S. Pat. No. 6,179,373 describe a shade arrangement in which the side edges of a length of shade are made such that they engage laterally attached, body-mounted guide rails such that they can be easily moved in the opening and closing motion of the shade, but cannot be pulled out of the guide rails transversely to the direction of shade motion. Thus, the edge regions of the shade length are protected against fluttering and vibration movements and at a corresponding distance of the guide rails on both sides compared to the width of the shade length the latter can be tensioned transversely to the drawing direction. The side edges of the shade length are provided with edge stiffeners for this purpose which can be kinked for engaging angled guide regions relative to the plane of the shade length, but for taking up the shade length onto the roller tube they can be returned to their extended, unkinked flat position.
The above described shade arrangement, on the one hand, has the disadvantage that continuous bending of the edge stiffening along the bending line generates a critical region along which the shade arrangement or edge stiffening can be damaged and even tear by material fatigue. On the other hand, to guide this edge stiffening a connecting link is required which borders the edge stiffening as it is guided and thus cannot be extruded; this increases construction and installation costs for this guide.
One aspect of the invention relates especially to the spring for tensioning the shade length in the drawing direction of the shade. To keep the shade length tensioned in any position in this lengthwise direction, in conventional shade arrangements the roller tube is connected to a central take-up shaft which is supported on the body within the roller tube via a reset spring, such as, for example, a torsion spring. This system is disclosed, for example, in German Patent DE 198 34 777 C2. With the shade length drawn, a tension force is applied to the shade length by such a reset spring via the roller tube. However, the disadvantage in this arrangement is the reset force of a torsion spring which varies greatly depending on the drawing length of the shade length.